Milling-cutter.



6 77- Patent odiluly I, 1902. I -B. m. w. HANSON.

MILLING CUTTER.

(Application filed July 5, 1901.)

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W 1Lln cssas: Q Inventof v JjW/(W 13.261147661213070 UNITED STATES I PATENT OFFICE.

BENGT M. W. HANSON, OF HARTFORD, CONNECTICUT, ASSIGNOR. TO PRATT 8t WHITNEY COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OF NEW JERSEY.

MILLING-CUTTER.

SPECIFICATION forming part of Letters Batent No. 703,577, dated July 1, 1902.

Application filed July 5, 1901. Serial No. 67,110. (No model.)

To all whom it may concern:

Be it known that I, BENGT M. W. HANSON, a citizen of Sweden, and a resident of Hartford, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Milling-Cutters, of which the following is a specification.

This invention relates to the milling-cutters employed for forming various contours, the object of the invention being to provide an improved'cutter having the contour of its teeth relieved at suitableinterval's toperniit the ready access of oil to the'succeeding'cutting edges of the tool and to permit the chips to roll up more freely.

Figure 1 of the drawings is a side view of a milling-cutter embodying the present invention, showing it in operative relation to a piece of Work. Fig. 2 is an edge view of the cutter in section, taken on the line 2 2 of Fig.

1. Fig. 3 is an edge view in enlarged scale; showing a fiat development of the teeth of the cutter of Figs. 1 and 2.; Figs.4, 5, and 6 are plan views showinga shaft having a screw-thread milledthereon, the three-views showing different teeth of' the cutter of the preceding figures in operative relation to the cut. The tooth of thecutter shown in Fig. 4. is relieved on the right-hand side, the tooth shown in Fig. 5 is relieved on the left-hand side, while the tooth shown in Fig. 6-has no relief on either side, therebeing preferably at least one such tooth provided in each cutter.

In the use of milling-cutters for forming contours which are not in a straight line two principal difficulties are encountered: first, that of conveying a supply of oil directly to the cutting edges of the succeeding teeth as they follow each other through the cut, this difficulty being due largely to the fact that each tooth is ordinarily made of the full contour to be formed, and each tooth therefore effectually stops and wipes-out of the out all of the oil conveyed therein, thus allowing practically no oil to pass to any succeeding tooth until its preceding tooth has emerged from the cut. The second difficulty is that of rolling up the chip which is carved from a contour'departing to any extent from'a straight line, the difficulty increasing with theangularity of the contour. These difficulties are obviated by the present invention. The cutter 10, aside from the features of the present improvement, is of a well-known a type, having a concentric bore 11 and a keyway 12, by which it is mounted upon and driven by a suitable mandrel. The periph I eral cutting-teeth are in the example herein illustrated of a contour suitable for milling the flat-bottomed V-thread shown upon the shaft shown in Figs. 4, 5, and 6. As hitherto made theteeth of such cutters are all of the full desired contour, as represented by the tooth 16of Fig. 6.

In this improvement portions of the contour of these teeth are 'relieved, as shown at 13 and 14. in Figs. 2, 4, and 5, the unrelieved or cutting edges being indicated by the numeral 15 in each case. In practice and for most purposes it is deemed advisable to relieve the same portion of alter- 7o nate teeth, as shown in Figs. 1 and 3. It is also preferred, whenever the number of teeth and the contour thereofwill permit, to provide the relief on alternately opposite sides.

of the succeeding teeth, as is also shown in In that case, however, the relieved unrelieved portions of immediately adjacent teeth should overlap, so that the complete contour to be formed is outlined by a small number of succeeding adjacent teeth. In the cutter shown in the drawings the contour being simple is complete in any two adjacent teeth.

The preferred relation of the teeth'of the contour shown in the drawings is bestillustrated in the diagrammatic view of Fig. 3, which represents in enlarged scalea flat development of the teeth of the cutter of Fig. 0

1 viewed from the outer peripheral edge thereof. The lines 21 and 22 represent the planes of the outer corners of the contour to be out by the tool, while lines 23 and ,24 represent the planes of the flat sides of the cutter. The unrelieved corners of the teeth are drawn in coincidence with these lines, while the relieved sides 14 of the teeth are shown inside of the lines.

For convenience in the manufacture of these cutters the relieved portion is preferably milled below the cutting contour before the cutter is hardened. After hardening the cutter the contour-cutting surfaces thereof are preferably ground to size with a suitable cutting clearance, as is customaryin tools of this class. The cutting-faces of the teeth are shown in Fig. 1 by a double line, representing the flats thatwould he formed upon the cutting edges in grinding them to the required contour, while the relieved or noncutting edges are represented by a single line.

When using these cutters for the milling of screw-threads, it is preferable to incline the plane of the cutterinto substantial coincidence with the angle formed by the spiral, and where the inclination is considerable the contour of the teeth should be correspondingly narrowed or otherwise modified to compensate for the inclination.

The action of the relieved portions of the teeth in permitting the passage of the oil to the succeeding teeth and the consequent desirability of having these relieved portions on the alternately opposite sides of the succeeding teeth are best understood from Figs. 1, 4, and 5. The direction of rotation of the screwshaft 17 which is beingmilled is indicated by the respective arrows l8, and the oil, which is most advantageously supplied from above in the direction of the arrow 19, flows into the scarf or cavity which is being milled out between the adjacent threads of the screw. If the teeth were all of the full contour, as represented by the tooth in Fig. 6, each one would sweep the oil out clean along with the chip, leaving a dry and closed channel behind for the succeeding teeth; but by relieving the alternate teeth, like those of Figs. 4 and 5, the oil flows readily past the relieved portions of each tooth to the succeeding tooth, and by alternating these relieved portions on the succeeding teeth, as shown in Fig. 3, the oil can easily flow to all the teeth in the cut sufiiciently to keep the work and the cutter cool. The cutting edge of each tooth is thus immediately behind the relieved portion of the preceding tooth, and therefore immediately in the pathway of the oil which passes that relieved portion.

For convenience in forming the teeth of these cutters it is desirable to have at least one tooth, as 16, carrying the full contour-'- that is to say, to leave one tooth entirely unrelieved, like that of Fig. 6since this facilitates the grinding and gaging of the cutter and also facilitates setting or adjusting it in the desired relation to the work to be done.

While the drawings and the foregoing description set forth my preferred construction and arrangement of this milling-cutter for the particular purpose shown, it will be obvious to those familiar with the manufacture and use of milling-cutters that it may be adapted to many diverse purposes; also, that the form and number and proportions of the teeth may be modified in accordance with the well-known requirements of different classes of work and materials to be milled.

These cutters may be used for the milling of contours in a plane surface, as well as on a peripheral surface, and may be employed singly or in gangs, as the nature of the work may permit or require.

The term relieved is herein used in its more general sense of being sunk below adjacent parts and not in the specific and technical sense in which the term is sometimes employed as applied to cutting edges having reference to the backward bevel or clearance which is provided on the rearward sides of cutting edges to facilitate their cutting action.

I claim as my invention- 1. A contour-milling cutter having one or more teeth of the full contour to be cut, and having some of the remaining teeth relieved below the contour at different portions of succeeding teeth.

2. A thread-milling cutter, provided with closely-adjacent integral teeth, having the contour of a truncated V, the succeeding teeth being relieved slightly below the cutting contour on alternately opposite sides, whereby the chips are cleared out of the out by each tooth while providing for the flow of oil directly to the cutting edges of the succeeding teeth.

Signed at Hartford, Connecticut, this 29th day of June, 1901.

B. M. \V. HANSON.

Witnesses:

F. V. BARTLETT, WM. 11. HoNIss. 

